Impact of fatty acids unsaturation on stability and intestinal lipolysis of bioactive lipid droplets

Emulsions are complex mixtures of immiscible liquids that are widely spread in foods and considered as natural, efficient and cost effective tools to deliver lipophilic bioactives to the consumer. Many recent studies seek to elucidate the principles for formulating emulsions with novel bioactive ingredients, such as bovine lactoferrin or bioactive lipids, towards enhanced and extended emulsion functionality. This research evaluated the effects of droplet lipid unsaturation degree on emulsion properties, stability and susceptibility to intestinal lipolysis. For this purpose, emulsions were produced via high pressure homogenization using extra virgin olive oil (EVOO) rich in 18:1n9 oleic acid, hemp seed oil (HSO) rich in 18:2n6 linoleic acid and pomegranate seed oil (PSO) rich in 18:3n5 conjugated linolenic acids (CLnA). Droplet fatty acid composition was altered using glyceryl trioleate (TOLN) doping at varying concentrations (1%, 2%, 5% and 10% [w/w]) and found to temper emulsion stability, droplet size, droplet size distribution spans. In respect to intestinal lipolysis, TOLN did not affect EVOO lipolysis, had mild impact on HSO lipolysis and markedly accelerated and enhanced the lipolysis of PSO. Fatty acid profiling of intestinal digesta indicated the preferential liberation of saturated, then monounsaturated and lastly polyunsaturated fatty acids from the various lipid droplets. Overall, the results presented herein show a new possibility for smart design of emulsions with sustained and controlled release of unsaturated fatty acids in the human gut.